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Publication Abstract from PubMed

G-protein-coupled receptors (GPCRs) transmit extracellular signals to activate intracellular heterotrimeric G proteins (Galphabetagamma) and arrestins. For G protein signalling, the Galpha C-terminus (GalphaCT) binds to a cytoplasmic crevice of the receptor that opens upon activation. A consensus motif is shared among GalphaCT from the Gi/Gt family and the 'finger loop' region (ArrFL1-4) of all four arrestins. Here we present a 2.75 A crystal structure of ArrFL-1, a peptide analogue of the finger loop of rod photoreceptor arrestin, in complex with the prototypical GPCR rhodopsin. Functional binding of ArrFL to the receptor was confirmed by ultraviolet-visible absorption spectroscopy, competitive binding assays and Fourier transform infrared spectroscopy. For both GalphaCT and ArrFL, binding to the receptor crevice induces a similar reverse turn structure, although significant structural differences are seen at the rim of the binding crevice. Our results reflect both the common receptor-binding interface and the divergent biological functions of G proteins and arrestins.

Crystal structure of a common GPCR-binding interface for G protein and arrestin.,Szczepek M, Beyriere F, Hofmann KP, Elgeti M, Kazmin R, Rose A, Bartl FJ, von Stetten D, Heck M, Sommer ME, Hildebrand PW, Scheerer P Nat Commun. 2014 Sep 10;5:4801. doi: 10.1038/ncomms5801. PMID:25205354^[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.